Police Minister Judith Collins says young people who feel police bully them into giving DNA samples should complain to the Independent Police Complaints Authority (IPCA).

Police can collect voluntary DNA samples only from people over 14 under strict guidelines when investigating a crime scene, but those guidelines will be relaxed from next month, meaning people aged 14 to 17 can be required to give samples under certain conditions if they are likely to face charges.

Maori Party MP Hone Harawira yesterday said he had heard of cases where young Maori were being "conned" by police into providing samples when they hadn't committed any crime.

"One young Maori told me the police wanted the sample because one of their relatives 'might be known' to the police," Mr Harawira said.

He accused police of using Nazi-style tactics and wanted them to desist or he would advise the young people in question to engage a lawyer and sue.

Mr Harawira said until Ms Collins could give an assurance that police had been "pulled into line" he would recommend all young Maori refuse to give voluntary DNA samples.

Criminal lawyer Graeme Newell raised concerns on Radio New Zealand this morning.

He said young people that would normally get a warning to change behaviour would now get taken into the police station and become part of the system, because police had the opportunity to get DNA. A boy had told him police offered him a cigarette in return for his DNA sample.

Ms Collins said Mr Newell and Mr Harawira should report concerns to IPCA or Police Commissioner Howard Broad. Asked if young people may not feel empowered to make a complaint Ms Collins said there were plenty of lawyers and MPs who would assist them.

The public could be confident that any complaint would be robustly investigated, she said.

She condemned Mr Harawira's use of the Nazi analogy and said it was offensive.

"I would also say look it's Hone we know he can sometimes make comments that are unfortunate and New Zealand police are very robust people. They deal with insults day in and day out although they should never have to put up with that sort of thing."